In a conventional exposure device, a mask pattern is exposed onto a substrate by emitting exposure light from a light source, and illuminating the substrate with the exposure light through a mask in which a pattern of predetermined shape has been formed. Therefore, alignment of the relative positions of the mask and the substrate is crucial for the purposes of exposing the pattern onto a predetermined position on the substrate with high accuracy. For example, Patent Document 1 discloses an exposure device of proximity exposure design, in which a wafer targeted for exposure use is positioned in proximity to the mask. Both the mask and the wafer are furnished with marks, and relative position alignment of the mask and the wafer is accomplished through these marks.
More recently, meanwhile, with the advent of microlens arrays, exposure devices that project a mask pattern onto a substrate have come into use. FIG. 44 is a schematic view showing an exposure device that uses a microlens array. Above a substrate 1 targeted for exposure, a mask 2 in which has been formed a pattern for exposure onto the substrate 1 is arranged at an appropriate gap relative to the substrate 1. Next, a microlens array 3 of microlenses 4 arrayed two-dimensionally is arranged between the substrate 1 and the mask 2, and the mask 2 is irradiated with exposure light from above the mask 2, the exposure light transmitted through the mask 2 being projected onto the substrate 1 by the microlens array 3, whereupon the pattern formed in the mask 2 is transferred as an erect unmagnified image by the microlens array 3 onto a resist or the like on the substrate surface.
In this case, normally, the mask 2 and the substrate 1 are stationary, while the microlens array 3, the exposure light source, and the optical system are moved in unison in a direction perpendicular to the plane of the page, to thereby scan the exposure light over the substrate 1. In this case, it is necessary to respectively furnish the top surface and the bottom surface of the substrate 1 with alignment marks 1a and 2a, and to align the relative positions of the substrate 1 and the mask 2 using these alignment marks 1a and 2a as guides.